Synthesis of morphology-controlled ZnO microstructures via a microwave-assisted hydrothermal method and their gas-sensing property

• ZnO could be rapidly synthesis by microwave-assisted hydrothermal.
• Seven-spine, flower-like, urchin-shaped and rod-like ZnO could be fabricated.
• The morphology of ZnO could be controlled by changing the [Zn2+].
• The size of ZnO was uniform after ultrasonic treatment.
• The gas-sensing property of ZnO was found to be highly morphology dependent.

Controllable ZnO architectures with flower-like and rod-like morphologies were synthesized via a microwave-assisted hydrothermal method. By adjusting the concentration of Zn2+ in the aqueous precursors, different morphologies of ZnO microstructures were obtained. The size of ZnO was uniform after ultrasonic treatment. The growth process of ZnO in solution was studied by monitoring the intermediate products, which were extracted at different stages of the reactions: (i) precursor preparation, (ii) microwave irradiation heating, (iii) natural cooling. Studies of the SEM images and XRD data revealed that the formation of ZnO occurred via in situ assembly or dissolution–reprecipitation of zinc hydroxide complexes. The morphology-dependent ethanol sensing performance was observed; the seven-spine ZnO structures exhibit the highest activity.